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Posted: Fri Nov 02, 2007 2:14 pm
by wvandyck
vier-personen wrote:I didn‘t read the whole thread so I might be OT already, but I recently bought this fairly cheap phono preamp (70•‚¬), and I am satisfied with it:

http://www.project-audio.com/main.php?p ... es&lang=en
Thanks for posting this. It's from the folks who made my turntable.
Based on my quick look around, I bet it sounds much better than the ART DeeJayPre (which I was considering as a quick but cheap solution).

Does anyone know what the pro or con is of a dual mono design?

I notice two different pictures of the same model online:
http://www.musiciansfriend.com/product/ ... sku=807601

or
http://www.avland.co.uk/pro-ject/phonob ... boxmk2.htm

Posted: Fri Nov 02, 2007 2:17 pm
by wvandyck
Phil O wrote:Good stuff! Thanks for the links. Phil
How about a quick summary when you finish reading them? :D

Posted: Fri Nov 02, 2007 6:03 pm
by mhschmieder
Dual mono is often referred to as "mono blocking", and generally means two separate amplifier blocks are needed vs. just one unit. All of the equipment that I have seen in that category is so expensive that I haven't delved deeply into the topic, but my guess is that the main advantage is avoiding any crosstalk between the two channels, as well as allowing a scalable architecture for supporting multi-channel formats.

Off-hand, the two amps I know of that are mono-blocked are the Manley tube preamp series (all except the Shrimp), and some of Bryston's newer LP-series power amps (which I think might be tube-based). So a search on those two product lines will likely give you some very good technical descriptions of the benefits of dual-mono vs. stereo. I've read the literature at both sites, but didn't bother committing it to memory as I felt in my budget range it was never going to apply.

Posted: Fri Nov 02, 2007 6:05 pm
by airtime
it's just an approximation. tweakable to taste.

Posted: Sat Nov 03, 2007 6:33 am
by wvandyck
mhschmieder wrote:Dual mono is often referred to as "mono blocking", and generally means two separate amplifier blocks are needed vs. just one unit. All of the equipment that I have seen in that category is so expensive that I haven't delved deeply into the topic, but my guess is that the main advantage is avoiding any crosstalk between the two channels, as well as allowing a scalable architecture for supporting multi-channel formats.
So, it sounds like the Project Phone Box has a high-end design feature.

I've given some thought to points you made previously:
1. Losing detail by coming into the A/D interface at low volumes before the RIAA curve is applied. This would certainly be a concern when optimal sound quality is required by a client, or by one with golden ears. I'm guessing that applying the eq curve and boosting volume after conversion will not have a high resolution compared to going through a phono preamp into the A/D.

Once the dust settles, I'll post an example of sound going into the A/D straight compared to passage through a phono preamp first.

But for the purposes of converting vinyl to listen to at home or in the car, airtimes suggestion fits my budget.

2. The sequence of eq and gain staging. You mentioned that the RIAA curve may come first, then the gain stage for the phono preamp. Again, I'll check this out to see what effect the order has on the sound.

3. Your suggestion to use acoustic piano, classiscal or jazz recordings as test material due to it's wide dynamic range.

At this point, I've ruled out the ART, and the Radial J33 for which I could not find any online discussion pro or con.

So my immediate options are to use airtimes method of applying the RIAA curve and gain as an intermediate solution :D :idea: :D, or lug the DAT machine downstair to connect to the receiver :?

Then it's a matter choosing one of the following:
1. The Project Phono Box
2. The Graham Slee Amp 2
3. Turntable that has a built-in preamp.

This has been a very helpful thread.
Thanks to all.

Posted: Sat Nov 03, 2007 9:06 am
by Phil O
flashgerkin wrote:
Phil O wrote:Good stuff! Thanks for the links. Phil
How about a quick summary when you finish reading them? :D
Didn't read the whole thing really. I was mostly interested in the discussion of the "improved" versions of the RIAA curve. I designed a preamp using the "old" specs (75us, 318us, 3180us) about 25 years ago for which I still have the prototype kicking around somewhere. I was thinking about modifying it with the added specs to see what the sonic differences would be.

Phil

Posted: Sat Nov 03, 2007 1:09 pm
by mhschmieder
I forget whether this was already covered here or not, but I thought I should just summarise the main purpose of the RIAA curve, which was to allow greater dynamic range and extended frequency response compared to what early vinyl production came up against regarding the limitations of pressing plants an d playback equipment.

In particular, the bass frequencies were cut, to prevent the stylus from jumping due to the combination of deep grooves and long waveforms. I think the higher frequency cuts were more related to maximising S/N ratio. But as you can see from the diagrams, it is not a "simple" curve, and took a lot of trial and error (and science) to get right.

And as Phil O says in his post, the RIAA curve was improved over time. I don't remember the timeframe though, and whether there were any compatibility issues, but usually in the audio industry things are done in such a way that nothing is glaringly wrong but that the newer scheme is more idealised. For example, the different flavours of dolby NR for tape.

Re: Affordable phono preamps for vinyl restoration?

Posted: Mon Oct 25, 2010 4:23 pm
by mhschmieder
I am revisiting this question as I recently parted with my audio pre-amp and standalone CD player and decided to go the all-computer route, for simplicity and consistency of routing and quality of the overall signal path for digital sources.

I now have a Radial JDI Duplex for most analog sources, leaving just the turntable as orphaned at the moment.

So, I revisited the Graham Slee webpage and found that they have refactored their entire line-up since I last checked. The irony is that it seems the cheaper model is now the better one, out-of-box without doing the power supply upgrade that is recommended for the mid-range unit.

That is, the low-end unit now has a built-in power supply that is good quality; whereas the mid-range unit ships with a mediocre one that begs to be upgraded with the standalone power supply (a bit expensive). Most people recommend just moving up to the $1000 unit at that point, which comes with a quality power supply.

I re-found this page while searching for current reviews and comparisons (I didn't find any). I was glad to find this thread as it reminded me why the Radial J33 (named for 33-1/3 records, apparently), is not the best option (though it would probably suffice, considering the source material that I'll be throwing at it, and my turntable and cartridge combination).

Re: Affordable phono preamps for vinyl restoration?

Posted: Mon Oct 25, 2010 4:30 pm
by mhschmieder
I should also add that I just upgraded from RX to RX 2 Advanced this past weekend, and have finally put my high-end Onkyo Integra TA-2800 cassette deck in the shop after it not working for eight years, so I'm definitely in a position now to start doing some serious audio restoration and digital conversions of legacy analog material on vinyl and tape!

Re: Affordable phono preamps for vinyl restoration?

Posted: Mon Oct 25, 2010 4:46 pm
by mhschmieder
To augment the earlier posts, it is worth stating what was implied:

The RIAA curve didn't stabilize until the mid-60's, so there are several in play (and the U.K. was different than the U.S.). Some of the better phono pre-amps are able to analyze the frequency spectrum of the material to figure out which RIAA curve was in use (if any), and some have a switch to dial it in (usually the higher-end phono pre-amps).

I would guess that the cheaper units, such as the Radial J33, have a single mid-60's-and-beyond RIAA curve that they automatically apply (although maybe it is switchable, such as when playing back old 78's).

I'll try to find a link to the J33 manual to download and study, hoping it divulges more details than the simple product spec sheet.

OK, here's the webpage that provides links for various J33 specs:

http://www.radialeng.com/di-j33-resources.htm

Re: Affordable phono preamps for vinyl restoration?

Posted: Mon Oct 25, 2010 4:50 pm
by mhschmieder
Unfortunately, the J33 won't cut it for most people, unless they only have US vinyl from the mid-50's on, and no UK vinyl.

It only uses the one RIAA curve from 1954, which I understand was standardized internationally in the mid to late 60's, meaning that US vinyl is pretty consistent from 1955 onwards but British vinyl is all over the map, and earlier US vinyl is questionable.

Re: Affordable phono preamps for vinyl restoration?

Posted: Tue Nov 09, 2010 1:18 am
by MaoZhengfu
I've been using a Cambridge Audio Azur 640P preamp for awhile and have gotten some great feedback from clients. It's definitely affordable and it sounds great.

http://www.cambridgeaudio.com/summary.php?PID=29" onclick="window.open(this.href);return false;

Re: Affordable phono preamps for vinyl restoration?

Posted: Wed Nov 10, 2010 1:20 pm
by mhschmieder
Yep, that's a pretty good one, but generally gets beat out by the similarly-priced Graham Slee Communicator (and higher-end models) -- especially for reliability -- so I took it off my list, but as it is easy to find used, it can be a great mid-to-high quality budget alternative (search AudioGon.com).

Re: Affordable phono preamps for vinyl restoration?

Posted: Thu Nov 11, 2010 9:37 am
by Phil O
I built one back in the seventies. Never got to the point where I put it in an enclosure. It just sat there, two naked circuit boards and a transformer on a piece of foam next to my turntable. Worked great. I was actually looking for it the other day. I know it's in a box somewhere in the attic or maybe the basement. Dunno. Never found it. Hope my wife didn't throw it out. :shock:

Phil

Re: Affordable phono preamps for vinyl restoration?

Posted: Sun Jan 15, 2012 6:39 am
by AndreaT
Dear All, I am pleased to inform you that I did an Audiophile Grade implementation of the following Phono RIAA Equalizations/De-emphasis:

Versions optimized for 44.1 and 48 kHz sampling:
- Official Standard RIAA (1964)
- IEC RIAA (IEC 60098) (1974)
- AT IEC RIAA (2012) - Own optimized version to digitally reduce hum & rumble

Versions optimized for 88.2 and 96 kHz sampling:
- Official Standard RIAA (1964)
- IEC RIAA with Neumann Correction (1995)
- AT IEC RIAA with Neumann Correction (2012) - Own optimized version to digitally reduce hum & rumble

The six EQ settings are provided as six XML configuration files to be imported or hand copied (the EQ section only) into your default/target configuration.

For only 19.90 USD I provide the EQ-files and 1 year maintenance support (any optimization and or adjustment to new MOTU FW version release).

The current implementations can work with the MOTU devices that fully support the MOTU Vintage Parametric EQ (i.e.: the new 896 mk3, 828 mk3, UltraLite mk3 and all the legacy and older having the same parametric EQ).

Do not hesitate to contact me for further details and purchase.
Kind regards,
Andrea Tarasconi